Prox Switch Woes

[setc]

New bot here (PRS standard 96x48), everything seems to be working great. Have all systems running great and table and carraiges are squared. However, the proximity switches are not working... at all. I have jumped input 3 to the input ground on the board and the input is reading fine. I also chacked the 5+, and it is at voltage. Re-wire both switches and the table is grounded properly. I even took a single witch off the bot, grounded it and moved the target infront of it and i still receive no reading.

So whats going on? (i'm also assuming the blue wire is the ground wire... the manual says green, and i know these type of sensors need a ground ref...)

thanks alot

[setc]

Oh,

So i dug the spec sheet that came with the prox switches out of the trash, and its rated for 10-30Vdc... The input com voltage is 5... So where do i plug the switch hot into? I can find a few places to plug them in, beeing there are two PSs in the control box... but i'll aire on the side of caution and wait till someone tells me.

[setc]

So, since no one has chimed in... its a sunday, i guess everyone is cooking on the grill or relaxing. I decided to test the switches according to the baumer website. They work and how. So i figured they must have some other power source. So i used the +12 on the outputs terminal block. HOWEVER, now the switches are normaly tripped, not allowing me to move unless i disable limit checking. Plus, i can't use any home to prox switch program becuase they are tripped instead of open, (error message appears: use keypad to move off of limit switches')...

[randy]

Geoffrey,

Maybe this thread will help:

http://www.talkshopbot.com/forum/messages/7/21211.html

[Brady Watson]

As a new owner, you'll want to check the downloads page under Support on the main web site often for updates and late breaking info regarding your tool. Pull down the PRS Assembly Manual (http://www.shopbottools.com/files/SBG00315070515PRSAssemblyManual.pdf) and read specifically page 52, which shows this diagram:


3931

-B

[richards]

Geoffrey,

If you're using version SB3 version 3.5.3, you can change the way the software treats the input switch (Normally Open or Normally Closed) with the VN command. I'm guessing that your switches are the Normally Closed type and that the VN setting is set to the Normally Open type. Change that to Normally Closed for the #2 and #3 inputs and you should be good to go.

[bill.young]

Geoffrey,

Make sure you're running the newest version of the ShopBot software, version 3.5.3 . There's some discussion of it in this thread...

http://www.talkshopbot.com/forum/messages/7/21441.html?1181163485

Bill

[setc]

thanks guys,

was perusing the website last night and stumbled upon that page, too. The side bar links change and i didn't notice that. (how observant me)! Anyways, thanks all. Got it up and running. Now why did they choose to use two imputs for the prox switch system? Running parallel into one on a normaly closed switch should yield good results as long as the unused switch isnt tripped.

I have a standard... i only have 4 inputs... they are all used... Waaahhhh! (althought i could use the z zero switch...)

[bill.young]

Hey Geoffrey,

You can't run 2 normally-closed switches off of just one input because the "untriggered" switch will keep the circuit closed even if the other prox switch triggers and opens. The earlier ShopBots had normally-open switches which could be connected to the same input...but not the normally-closed ones.

And check again in your Control box...the PRSstandard tools can use 8 input switches just like the PRSalphas

Bill

[paco]

Out of curiosity, do the current homing routine go diagonally? I'm asking because I noticed the wiring (above) and see that it use two inputs. My guess is that it's because the new sensors are normally close so that the system know if the sensor are working correctly and "safely" with this wiring and from there normal state... but when I install mine, I consider a new routine that would have homed the X & Y independently with a diagonally moving approach... faster process... this what I mostly saw before on other CNC tools...

I finally wired my (N.O.) sensors as PRT fashion (together/one input) though.

There's noting wrong with the old "one axis at a time" way; I was just wondering if there's something new that I missed...

[richards]

Paco,
The main problem with Normally Open switches is that you don't know whether the absence of a switch closure is caused by a faulty switch or whether it is caused by the switch not being activated. With a Normally Closed switch, the circuit is always active until the switch 'senses' the metal proximity object. It's the same philosophy upon which the newer Normally Closed E-stop switches are based. An even better solution (in my opinion) is to use Normally Open proximity switches, but to have the switches sense a strip of metal (perhaps the rail) except where the 'limit' is and then have a hole in the metal to 'release' the Normally Open switch. That is a little more difficult to implement, but it is even more 'fail-safe' than using a Normally Closed switch.

[byoc]

Does anyone with the new style prox switches find them to be too sensitive? Everytime I run a file, they are garuanteed to trip before the job is done.

[richards]

Keith,
On my PRT-Alpha, I machined the head of the target bolt flat. If you don't have a metal cutting lathe, you could use a file. Also, if the sensor is picking up false-positives, increase the distance between the sensor and the 'bolt' a little. I don't know the rating of your sensors, but 'standard' switches have ratings of 2mm, although some have a distance rating of 4mm. Use a feeler guage between the switch and the target and increase the distance about 0.020" at a time. When the switch no longer senses the target, decrease the distance about 0.020" and you should have a working switch that is stable.

[Gary Campbell]

Keith...
I had one or the other prox switches tripping every few seconds while running a file. It was not the switches... call or email SP support for the grounding fix.
Gary